An engine of a vehicle may be stopped during selected conditions to conserve fuel. The conditions that allow the engine to stop may change while the engine is being stopped so that the engine may be restarted before engine rotation is completely stopped. For example, a driver may release a brake pedal shortly after fuel injection to engine cylinders stops. The engine may be restarted by resuming fuel injection. However, engine speed may be reduced to a lower level where the engine may not be restarted by simply reactivating fuel to engine cylinders. One way to restart the engine at lower engine speeds is to engage a starter and provide engine cranking assistance if the driver has a change of mind. However, engaging the starter may change the engine speed profile and affect engine emissions.
The inventors herein have recognized the above-mentioned disadvantages and have developed a method for stopping rotation of an engine, comprising: ceasing fuel delivery to engine cylinders combusting air and fuel; commanding engagement of a starter from a state not engaged with the engine to engaged with the engine; and adjusting a position of a throttle based on whether or not the starter engages the engine.
By adjusting a position of a throttle during engine stopping in response to whether or not the starter engages the engine, it may be possible to improve engine stopping so that subsequent engine starting is improved. In particular, an actuator such as a throttle may be adjusted during an engine stop in response to whether or not a starter engages an engine so that the engine may be readied for starting. For example, if the starter engages the engine it may be desirable to partially open the throttle an increased amount so that additional torque may be provided if an operator has a change of mind.
The present description may provide several advantages. Specifically, the approach may improve engine stopping by preparing the engine for restart. Further, the approach may improve control of engine stopping position via adjusting air entering cylinders during an engine stop.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.